The present invention relates to a variable valve operating apparatus for an internal combustion engine which controls opening and closing timings of an engine valve, i.e., an intake valve and/or an exhaust valve of the internal combustion engine.
Recently, there has been proposed a valve timing control apparatus as a variable valve operating apparatus adapted to control opening and closing timings of an intake valve and/or an exhaust valve of an internal combustion engine by using a rotational driving force of an electric motor.
For instance, Japanese Patent Application Unexamined Publication No. 2011-231700 A recites a valve timing control apparatus including an electric motor and a speed reducing mechanism for reducing a rotational driving force of the electric motor. The electric motor is a DC motor with brushes which includes a cylindrical motor housing constituting a stator, permanent magnets disposed on an inner peripheral surface of the motor housing along a circumferential direction of the motor housing, and a core rotor disposed on an inner peripheral side of the permanent magnets, the core rotor being fixed on an outer periphery of a motor output shaft and equipped with coil windings.
Further, a partition wall made of a metal is disposed between the electric motor and the speed reducing mechanism to separate the electric motor and the speed reducing mechanism from each other. The partition wall has an annular convex portion on an outer peripheral side thereof which is formed integrally with the partition wall. The annular convex portion has a threaded hole into which a tip end portion of a bolt is screwed to couple the motor housing and a casing of the speed reducing mechanism to each other in an axial direction thereof.
Further, the partition wall is arranged as close to the electric motor as possible in an axial direction of the electric motor so that the valve timing control apparatus is reduced in axial length thereof to thereby be downsized.